[clang] [CIR] Call code gen; create empty cir.func op (PR #113483)

[Nathan Lanza via cfe-commits]

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@@ -31,9 +34,14 @@ void CIRGenerator::Initialize(ASTContext &astCtx) {
 
   this->astCtx = &astCtx;
 
-  cgm = std::make_unique<CIRGenModule>(*mlirCtx, astCtx, codeGenOpts, diags);
+  mlirCtx = std::make_unique<mlir::MLIRContext>();
+  mlirCtx->getOrLoadDialect<mlir::cir::CIRDialect>();
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lanza wrote:

There's a `loadDialect` equivalent that we can switch to. 

https://github.com/llvm/llvm-project/pull/113483